/*
 The MIT License (MIT)
 
 Copyright (c) 2012-2016 Syoyo Fujita and many contributors.
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
 in the Software without restriction, including without limitation the rights
 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 copies of the Software, and to permit persons to whom the Software is
 furnished to do so, subject to the following conditions:
 
 The above copyright notice and this permission notice shall be included in
 all copies or substantial portions of the Software.
 
 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 THE SOFTWARE.
 */

//
// version 1.0.4 : Support multiple filenames for 'mtllib'(#112)
// version 1.0.3 : Support parsing texture options(#85)
// version 1.0.2 : Improve parsing speed by about a factor of 2 for large
// files(#105)
// version 1.0.1 : Fixes a shape is lost if obj ends with a 'usemtl'(#104)
// version 1.0.0 : Change data structure. Change license from BSD to MIT.
//

//
// Use this in *one* .cc
//   #define TINYOBJLOADER_IMPLEMENTATION
//   #include "tiny_obj_loader.h"
//

#ifndef TINY_OBJ_LOADER_H_
#define TINY_OBJ_LOADER_H_

#include <map>
#include <string>
#include <vector>
#include "VROLog.h"
#include "VROPlatformUtil.h"
#include "VROTaskQueue.h"

namespace tinyobj {
    
    // https://en.wikipedia.org/wiki/Wavefront_.obj_file says ...
    //
    //  -blendu on | off                       # set horizontal texture blending
    //  (default on)
    //  -blendv on | off                       # set vertical texture blending
    //  (default on)
    //  -boost float_value                     # boost mip-map sharpness
    //  -mm base_value gain_value              # modify texture map values (default
    //  0 1)
    //                                         #     base_value = brightness,
    //                                         gain_value = contrast
    //  -o u [v [w]]                           # Origin offset             (default
    //  0 0 0)
    //  -s u [v [w]]                           # Scale                     (default
    //  1 1 1)
    //  -t u [v [w]]                           # Turbulence                (default
    //  0 0 0)
    //  -texres resolution                     # texture resolution to create
    //  -clamp on | off                        # only render texels in the clamped
    //  0-1 range (default off)
    //                                         #   When unclamped, textures are
    //                                         repeated across a surface,
    //                                         #   when clamped, only texels which
    //                                         fall within the 0-1
    //                                         #   range are rendered.
    //  -bm mult_value                         # bump multiplier (for bump maps
    //  only)
    //
    //  -imfchan r | g | b | m | l | z         # specifies which channel of the file
    //  is used to
    //                                         # create a scalar or bump texture.
    //                                         r:red, g:green,
    //                                         # b:blue, m:matte, l:luminance,
    //                                         z:z-depth..
    //                                         # (the default for bump is 'l' and
    //                                         for decal is 'm')
    //  bump -imfchan r bumpmap.tga            # says to use the red channel of
    //  bumpmap.tga as the bumpmap
    //
    // For reflection maps...
    //
    //   -type sphere                           # specifies a sphere for a "refl"
    //   reflection map
    //   -type cube_top    | cube_bottom |      # when using a cube map, the texture
    //   file for each
    //         cube_front  | cube_back   |      # side of the cube is specified
    //         separately
    //         cube_left   | cube_right
    
    typedef enum {
        TEXTURE_TYPE_NONE,  // default
        TEXTURE_TYPE_SPHERE,
        TEXTURE_TYPE_CUBE_TOP,
        TEXTURE_TYPE_CUBE_BOTTOM,
        TEXTURE_TYPE_CUBE_FRONT,
        TEXTURE_TYPE_CUBE_BACK,
        TEXTURE_TYPE_CUBE_LEFT,
        TEXTURE_TYPE_CUBE_RIGHT
    } texture_type_t;
    
    typedef struct {
        texture_type_t type;     // -type (default TEXTURE_TYPE_NONE)
        float sharpness;         // -boost (default 1.0?)
        float brightness;        // base_value in -mm option (default 0)
        float contrast;          // gain_value in -mm option (default 1)
        float origin_offset[3];  // -o u [v [w]] (default 0 0 0)
        float scale[3];          // -s u [v [w]] (default 1 1 1)
        float turbulence[3];     // -t u [v [w]] (default 0 0 0)
        // int   texture_resolution; // -texres resolution (default = ?) TODO
        bool clamp;    // -clamp (default false)
        char imfchan;  // -imfchan (the default for bump is 'l' and for decal is 'm')
        bool blendu;   // -blendu (default on)
        bool blendv;   // -blendv (default on)
        float bump_multiplier;  // -bm (for bump maps only, default 1.0)
    } texture_option_t;
    
    typedef struct {
        std::string name;
        
        float ambient[3];
        float diffuse[3];
        float specular[3];
        float transmittance[3];
        float emission[3];
        float shininess;
        float ior;       // index of refraction
        float dissolve;  // 1 == opaque; 0 == fully transparent
        // illumination model (see http://www.fileformat.info/format/material/)
        int illum;
        
        int dummy;  // Suppress padding warning.
        
        std::string ambient_texname;             // map_Ka
        std::string diffuse_texname;             // map_Kd
        std::string specular_texname;            // map_Ks
        std::string specular_highlight_texname;  // map_Ns
        std::string bump_texname;                // map_bump, bump
        std::string displacement_texname;        // disp
        std::string alpha_texname;               // map_d
        
        texture_option_t ambient_texopt;
        texture_option_t diffuse_texopt;
        texture_option_t specular_texopt;
        texture_option_t specular_highlight_texopt;
        texture_option_t bump_texopt;
        texture_option_t displacement_texopt;
        texture_option_t alpha_texopt;
        
        // PBR extension
        // http://exocortex.com/blog/extending_wavefront_mtl_to_support_pbr
        float roughness;            // [0, 1] default 0
        float metallic;             // [0, 1] default 0
        float sheen;                // [0, 1] default 0
        float clearcoat_thickness;  // [0, 1] default 0
        float clearcoat_roughness;  // [0, 1] default 0
        float anisotropy;           // aniso. [0, 1] default 0
        float anisotropy_rotation;  // anisor. [0, 1] default 0
        float pad0;
        float pad1;
        std::string roughness_texname;  // map_Pr
        std::string metallic_texname;   // map_Pm
        std::string sheen_texname;      // map_Ps
        std::string emissive_texname;   // map_Ke
        std::string normal_texname;     // norm. For normal mapping.
        
        texture_option_t roughness_texopt;
        texture_option_t metallic_texopt;
        texture_option_t sheen_texopt;
        texture_option_t emissive_texopt;
        texture_option_t normal_texopt;
        
        int pad2;
        
        std::map<std::string, std::string> unknown_parameter;
        
        bool has_diffuse_color;
        bool has_illum;
    } material_t;
    
    typedef struct {
        std::string name;
        
        std::vector<int> intValues;
        std::vector<float> floatValues;
        std::vector<std::string> stringValues;
    } tag_t;
    
    // Index struct to support different indices for vtx/normal/texcoord.
    // -1 means not used.
    typedef struct {
        int vertex_index;
        int normal_index;
        int texcoord_index;
    } index_t;
    
    typedef struct {
        std::vector<index_t> indices;
        std::vector<unsigned char> num_face_vertices;  // The number of vertices per
        // face. 3 = polygon, 4 = quad,
        // ... Up to 255.
        std::vector<int> material_ids;                 // per-face material ID
        std::vector<tag_t> tags;                       // SubD tag
    } mesh_t;
    
    typedef struct {
        std::string name;
        mesh_t mesh;
    } shape_t;
    
    // Vertex attributes
    typedef struct {
        std::vector<float> vertices;   // 'v'
        std::vector<float> normals;    // 'vn'
        std::vector<float> texcoords;  // 'vt'
    } attrib_t;
    
    typedef struct callback_t_ {
        // W is optional and set to 1 if there is no `w` item in `v` line
        void (*vertex_cb)(void *user_data, float x, float y, float z, float w);
        void (*normal_cb)(void *user_data, float x, float y, float z);
        
        // y and z are optional and set to 0 if there is no `y` and/or `z` item(s) in
        // `vt` line.
        void (*texcoord_cb)(void *user_data, float x, float y, float z);
        
        // called per 'f' line. num_indices is the number of face indices(e.g. 3 for
        // triangle, 4 for quad)
        // 0 will be passed for undefined index in index_t members.
        void (*index_cb)(void *user_data, index_t *indices, int num_indices);
        // `name` material name, `material_id` = the array index of material_t[]. -1
        // if
        // a material not found in .mtl
        void (*usemtl_cb)(void *user_data, const char *name, int material_id);
        // `materials` = parsed material data.
        void (*mtllib_cb)(void *user_data, const material_t *materials,
                          int num_materials);
        // There may be multiple group names
        void (*group_cb)(void *user_data, const char **names, int num_names);
        void (*object_cb)(void *user_data, const char *name);
        
        callback_t_()
        : vertex_cb(NULL),
        normal_cb(NULL),
        texcoord_cb(NULL),
        index_cb(NULL),
        usemtl_cb(NULL),
        mtllib_cb(NULL),
        group_cb(NULL),
        object_cb(NULL) {}
    } callback_t;
    
    class MaterialReader {
    public:
        MaterialReader() {}
        virtual ~MaterialReader();
        
        virtual bool operator()(const std::string &matId,
                                std::shared_ptr<std::vector<material_t>> materials,
                                std::shared_ptr<std::map<std::string, int>> matMap,
                                std::string *err) = 0;
    };
    
    class MaterialFileReader : public MaterialReader {
    public:
        explicit MaterialFileReader() {}
        explicit MaterialFileReader(const std::string &mtl_basedir, bool baseurl, std::shared_ptr<VROTaskQueue> taskQueue)
        : m_mtlBaseDir(mtl_basedir), m_baseurl(baseurl), m_taskQueue(taskQueue), m_resourceMap(nullptr) {}
        explicit MaterialFileReader(std::map<std::string, std::string> *resourceMap, std::shared_ptr<VROTaskQueue> taskQueue)
        : m_taskQueue(taskQueue), m_resourceMap(resourceMap) {}
        virtual ~MaterialFileReader() {}
        virtual bool operator()(const std::string &matId,
                                std::shared_ptr<std::vector<material_t>> materials,
                                std::shared_ptr<std::map<std::string, int>> matMap,
                                std::string *err);
        
    private:
        std::string m_mtlBaseDir;
        bool m_baseurl;
        std::shared_ptr<VROTaskQueue> m_taskQueue;
        std::map<std::string, std::string> *m_resourceMap;
        
        static bool readMaterialFile(std::string filePath, const std::string &matId,
                                     std::shared_ptr<std::vector<material_t>> materials,
                                     std::shared_ptr<std::map<std::string, int>> matMap, std::string *err);
    };
    
    /// Loads .obj from a file.
    /// 'attrib', 'shapes' and 'materials' will be filled with parsed shape data
    /// 'shapes' will be filled with parsed shape data
    /// Returns true when loading .obj become success.
    /// Returns warning and error message into `err`
    /// 'mtl_basedir' is optional, and used for base directory for .mtl file.
    /// In default(`NULL'), .mtl file is searched from an application's working directory.
    /// 'triangulate' is optional, and used whether triangulate polygon face in .obj
    /// or not.
    
    /// Viro notes: this is called from any background thread, and will use an internal
    ///             task queue. When complete, the callback will be invoked on the
    ///             rendering thread.
    void LoadObj(std::shared_ptr<attrib_t> attrib, std::shared_ptr<std::vector<shape_t>> shapes,
                 std::shared_ptr<std::vector<material_t>> materials, std::string *err,
                 const char *filename, const char *mtl_basedir,
                 bool baseurl,
                 std::map<std::string, std::string> *resourceMap,
                 std::shared_ptr<VROTaskQueue> taskQueue,
                 std::function<void(bool)> onFinished,
                 bool triangulate = true);
    
    // Load all the MTL files into the given map, which can then be passed
    // into LoadObj
    bool LoadMTLFiles(std::shared_ptr<std::vector<material_t>> materials,
                      std::shared_ptr<std::map<std::string, int>> material_map,
                      std::string *err,
                      std::shared_ptr<std::istream> inStream, MaterialReader *readMatFn);
    
    /// Loads object from a std::istream, uses GetMtlIStreamFn to retrieve
    /// std::istream for materials.
    /// Returns true when loading .obj become success.
    /// Returns warning and error message into `err`
    bool LoadObj(std::shared_ptr<attrib_t> attrib, std::shared_ptr<std::vector<shape_t>> shapes,
                 std::shared_ptr<std::map<std::string, int>> material_map,
                 std::string *err,
                 std::shared_ptr<std::istream> inStream,
                 bool triangulate = true);
    
    /// Loads materials into std::map
    void LoadMtl(std::shared_ptr<std::map<std::string, int>> material_map,
                 std::shared_ptr<std::vector<material_t>> materials, std::shared_ptr<std::istream> inStream);
    
}  // namespace tinyobj

#ifdef TINYOBJLOADER_IMPLEMENTATION
#include <cassert>
#include <cctype>
#include <cmath>
#include <cstddef>
#include <cstdlib>
#include <cstring>
#include <utility>

#include <fstream>
#include <sstream>

namespace tinyobj {
    
    MaterialReader::~MaterialReader() {}
    
#define TINYOBJ_SSCANF_BUFFER_SIZE (4096)
    
    struct vertex_index {
        int v_idx, vt_idx, vn_idx;
        vertex_index() : v_idx(-1), vt_idx(-1), vn_idx(-1) {}
        explicit vertex_index(int idx) : v_idx(idx), vt_idx(idx), vn_idx(idx) {}
        vertex_index(int vidx, int vtidx, int vnidx)
        : v_idx(vidx), vt_idx(vtidx), vn_idx(vnidx) {}
    };
    
    struct tag_sizes {
        tag_sizes() : num_ints(0), num_floats(0), num_strings(0) {}
        int num_ints;
        int num_floats;
        int num_strings;
    };
    
    struct obj_shape {
        std::vector<float> v;
        std::vector<float> vn;
        std::vector<float> vt;
    };
    
    // See
    // http://stackoverflow.com/questions/6089231/getting-std-ifstream-to-handle-lf-cr-and-crlf
    static std::istream &safeGetline(std::istream &is, std::string &t) {
        t.clear();
        
        // The characters in the stream are read one-by-one using a std::streambuf.
        // That is faster than reading them one-by-one using the std::istream.
        // Code that uses streambuf this way must be guarded by a sentry object.
        // The sentry object performs various tasks,
        // such as thread synchronization and updating the stream state.
        
        std::istream::sentry se(is, true);
        std::streambuf *sb = is.rdbuf();
        
        for (;;) {
            int c = sb->sbumpc();
            switch (c) {
                case '\n':
                    return is;
                case '\r':
                    if (sb->sgetc() == '\n') sb->sbumpc();
                    return is;
                case EOF:
                    // Also handle the case when the last line has no line ending
                    if (t.empty()) is.setstate(std::ios::eofbit);
                    return is;
                default:
                    t += static_cast<char>(c);
            }
        }
    }
    
#define IS_SPACE(x) (((x) == ' ') || ((x) == '\t'))
#define IS_DIGIT(x) \
(static_cast<unsigned int>((x) - '0') < static_cast<unsigned int>(10))
#define IS_NEW_LINE(x) (((x) == '\r') || ((x) == '\n') || ((x) == '\0'))
    
    // Make index zero-base, and also support relative index.
    static inline int fixIndex(int idx, int n) {
        if (idx > 0) return idx - 1;
        if (idx == 0) return 0;
        return n + idx;  // negative value = relative
    }
    
    static inline std::string parseString(const char **token) {
        std::string s;
        (*token) += strspn((*token), " \t");
        size_t e = strcspn((*token), " \t\r");
        s = std::string((*token), &(*token)[e]);
        (*token) += e;
        return s;
    }
    
    static inline int parseInt(const char **token) {
        (*token) += strspn((*token), " \t");
        int i = atoi((*token));
        (*token) += strcspn((*token), " \t\r");
        return i;
    }
    
    // Tries to parse a floating point number located at s.
    //
    // s_end should be a location in the string where reading should absolutely
    // stop. For example at the end of the string, to prevent buffer overflows.
    //
    // Parses the following EBNF grammar:
    //   sign    = "+" | "-" ;
    //   END     = ? anything not in digit ?
    //   digit   = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" ;
    //   integer = [sign] , digit , {digit} ;
    //   decimal = integer , ["." , integer] ;
    //   float   = ( decimal , END ) | ( decimal , ("E" | "e") , integer , END ) ;
    //
    //  Valid strings are for example:
    //   -0  +3.1417e+2  -0.0E-3  1.0324  -1.41   11e2
    //
    // If the parsing is a success, result is set to the parsed value and true
    // is returned.
    //
    // The function is greedy and will parse until any of the following happens:
    //  - a non-conforming character is encountered.
    //  - s_end is reached.
    //
    // The following situations triggers a failure:
    //  - s >= s_end.
    //  - parse failure.
    //
    static bool tryParseDouble(const char *s, const char *s_end, double *result) {
        if (s >= s_end) {
            return false;
        }
        
        double mantissa = 0.0;
        // This exponent is base 2 rather than 10.
        // However the exponent we parse is supposed to be one of ten,
        // thus we must take care to convert the exponent/and or the
        // mantissa to a * 2^E, where a is the mantissa and E is the
        // exponent.
        // To get the final double we will use ldexp, it requires the
        // exponent to be in base 2.
        int exponent = 0;
        
        // NOTE: THESE MUST BE DECLARED HERE SINCE WE ARE NOT ALLOWED
        // TO JUMP OVER DEFINITIONS.
        char sign = '+';
        char exp_sign = '+';
        char const *curr = s;
        
        // How many characters were read in a loop.
        int read = 0;
        // Tells whether a loop terminated due to reaching s_end.
        bool end_not_reached = false;
        
        /*
         BEGIN PARSING.
         */
        
        // Find out what sign we've got.
        if (*curr == '+' || *curr == '-') {
            sign = *curr;
            curr++;
        } else if (IS_DIGIT(*curr)) { /* Pass through. */
        } else {
            goto fail;
        }
        
        // Read the integer part.
        end_not_reached = (curr != s_end);
        while (end_not_reached && IS_DIGIT(*curr)) {
            mantissa *= 10;
            mantissa += static_cast<int>(*curr - 0x30);
            curr++;
            read++;
            end_not_reached = (curr != s_end);
        }
        
        // We must make sure we actually got something.
        if (read == 0) goto fail;
        // We allow numbers of form "#", "###" etc.
        if (!end_not_reached) goto assemble;
        
        // Read the decimal part.
        if (*curr == '.') {
            curr++;
            read = 1;
            end_not_reached = (curr != s_end);
            while (end_not_reached && IS_DIGIT(*curr)) {
                static const double pow_lut[] = {
                    1.0, 0.1, 0.01, 0.001, 0.0001, 0.00001, 0.000001, 0.0000001,
                };
                const int lut_entries = sizeof pow_lut / sizeof pow_lut[0];
                
                // NOTE: Don't use powf here, it will absolutely murder precision.
                mantissa += static_cast<int>(*curr - 0x30) *
                (read < lut_entries ? pow_lut[read] : pow(10.0, -read));
                read++;
                curr++;
                end_not_reached = (curr != s_end);
            }
        } else if (*curr == 'e' || *curr == 'E') {
        } else {
            goto assemble;
        }
        
        if (!end_not_reached) goto assemble;
        
        // Read the exponent part.
        if (*curr == 'e' || *curr == 'E') {
            curr++;
            // Figure out if a sign is present and if it is.
            end_not_reached = (curr != s_end);
            if (end_not_reached && (*curr == '+' || *curr == '-')) {
                exp_sign = *curr;
                curr++;
            } else if (IS_DIGIT(*curr)) { /* Pass through. */
            } else {
                // Empty E is not allowed.
                goto fail;
            }
            
            read = 0;
            end_not_reached = (curr != s_end);
            while (end_not_reached && IS_DIGIT(*curr)) {
                exponent *= 10;
                exponent += static_cast<int>(*curr - 0x30);
                curr++;
                read++;
                end_not_reached = (curr != s_end);
            }
            exponent *= (exp_sign == '+' ? 1 : -1);
            if (read == 0) goto fail;
        }
        
    assemble:
        *result =
        (sign == '+' ? 1 : -1) *
        (exponent ? ldexp(mantissa * pow(5.0, exponent), exponent) : mantissa);
        return true;
    fail:
        return false;
    }
    
    static inline float parseFloat(const char **token, double default_value = 0.0) {
        (*token) += strspn((*token), " \t");
        const char *end = (*token) + strcspn((*token), " \t\r");
        double val = default_value;
        tryParseDouble((*token), end, &val);
        float f = static_cast<float>(val);
        (*token) = end;
        return f;
    }
    
    static inline void parseFloat2(float *x, float *y, const char **token,
                                   const double default_x = 0.0,
                                   const double default_y = 0.0) {
        (*x) = parseFloat(token, default_x);
        (*y) = parseFloat(token, default_y);
    }
    
    static inline void parseFloat3(float *x, float *y, float *z, const char **token,
                                   const double default_x = 0.0,
                                   const double default_y = 0.0,
                                   const double default_z = 0.0) {
        (*x) = parseFloat(token, default_x);
        (*y) = parseFloat(token, default_y);
        (*z) = parseFloat(token, default_z);
    }
    
    static inline void parseV(float *x, float *y, float *z, float *w,
                              const char **token, const double default_x = 0.0,
                              const double default_y = 0.0,
                              const double default_z = 0.0,
                              const double default_w = 1.0) {
        (*x) = parseFloat(token, default_x);
        (*y) = parseFloat(token, default_y);
        (*z) = parseFloat(token, default_z);
        (*w) = parseFloat(token, default_w);
    }
    
    static inline bool parseOnOff(const char **token, bool default_value = true) {
        (*token) += strspn((*token), " \t");
        const char *end = (*token) + strcspn((*token), " \t\r");
        
        bool ret = default_value;
        if ((0 == strncmp((*token), "on", 2))) {
            ret = true;
        } else if ((0 == strncmp((*token), "off", 3))) {
            ret = false;
        }
        
        (*token) = end;
        return ret;
    }
    
    static inline texture_type_t parseTextureType(
                                                  const char **token, texture_type_t default_value = TEXTURE_TYPE_NONE) {
        (*token) += strspn((*token), " \t");
        const char *end = (*token) + strcspn((*token), " \t\r");
        texture_type_t ty = default_value;
        
        if ((0 == strncmp((*token), "cube_top", strlen("cube_top")))) {
            ty = TEXTURE_TYPE_CUBE_TOP;
        } else if ((0 == strncmp((*token), "cube_bottom", strlen("cube_bottom")))) {
            ty = TEXTURE_TYPE_CUBE_BOTTOM;
        } else if ((0 == strncmp((*token), "cube_left", strlen("cube_left")))) {
            ty = TEXTURE_TYPE_CUBE_LEFT;
        } else if ((0 == strncmp((*token), "cube_right", strlen("cube_right")))) {
            ty = TEXTURE_TYPE_CUBE_RIGHT;
        } else if ((0 == strncmp((*token), "cube_front", strlen("cube_front")))) {
            ty = TEXTURE_TYPE_CUBE_FRONT;
        } else if ((0 == strncmp((*token), "cube_back", strlen("cube_back")))) {
            ty = TEXTURE_TYPE_CUBE_BACK;
        } else if ((0 == strncmp((*token), "sphere", strlen("sphere")))) {
            ty = TEXTURE_TYPE_SPHERE;
        }
        
        (*token) = end;
        return ty;
    }
    
    static tag_sizes parseTagTriple(const char **token) {
        tag_sizes ts;
        
        ts.num_ints = atoi((*token));
        (*token) += strcspn((*token), "/ \t\r");
        if ((*token)[0] != '/') {
            return ts;
        }
        (*token)++;
        
        ts.num_floats = atoi((*token));
        (*token) += strcspn((*token), "/ \t\r");
        if ((*token)[0] != '/') {
            return ts;
        }
        (*token)++;
        
        ts.num_strings = atoi((*token));
        (*token) += strcspn((*token), "/ \t\r") + 1;
        
        return ts;
    }
    
    // Parse triples with index offsets: i, i/j/k, i//k, i/j
    static vertex_index parseTriple(const char **token, int vsize, int vnsize,
                                    int vtsize) {
        vertex_index vi(-1);
        
        vi.v_idx = fixIndex(atoi((*token)), vsize);
        (*token) += strcspn((*token), "/ \t\r");
        if ((*token)[0] != '/') {
            return vi;
        }
        (*token)++;
        
        // i//k
        if ((*token)[0] == '/') {
            (*token)++;
            vi.vn_idx = fixIndex(atoi((*token)), vnsize);
            (*token) += strcspn((*token), "/ \t\r");
            return vi;
        }
        
        // i/j/k or i/j
        vi.vt_idx = fixIndex(atoi((*token)), vtsize);
        (*token) += strcspn((*token), "/ \t\r");
        if ((*token)[0] != '/') {
            return vi;
        }
        
        // i/j/k
        (*token)++;  // skip '/'
        vi.vn_idx = fixIndex(atoi((*token)), vnsize);
        (*token) += strcspn((*token), "/ \t\r");
        return vi;
    }
    
    static bool ParseTextureNameAndOption(std::string *texname,
                                          texture_option_t *texopt,
                                          const char *linebuf, const bool is_bump) {
        // @todo { write more robust lexer and parser. }
        bool found_texname = false;
        std::string texture_name;
        
        // Fill with default value for texopt.
        if (is_bump) {
            texopt->imfchan = 'l';
        } else {
            texopt->imfchan = 'm';
        }
        texopt->bump_multiplier = 1.0f;
        texopt->clamp = false;
        texopt->blendu = true;
        texopt->blendv = true;
        texopt->sharpness = 1.0f;
        texopt->brightness = 0.0f;
        texopt->contrast = 1.0f;
        texopt->origin_offset[0] = 0.0f;
        texopt->origin_offset[1] = 0.0f;
        texopt->origin_offset[2] = 0.0f;
        texopt->scale[0] = 1.0f;
        texopt->scale[1] = 1.0f;
        texopt->scale[2] = 1.0f;
        texopt->turbulence[0] = 0.0f;
        texopt->turbulence[1] = 0.0f;
        texopt->turbulence[2] = 0.0f;
        texopt->type = TEXTURE_TYPE_NONE;
        
        const char *token = linebuf;  // Assume line ends with NULL
        
        while (!IS_NEW_LINE((*token))) {
            if ((0 == strncmp(token, "-blendu", 7)) && IS_SPACE((token[7]))) {
                token += 8;
                texopt->blendu = parseOnOff(&token, /* default */ true);
            } else if ((0 == strncmp(token, "-blendv", 7)) && IS_SPACE((token[7]))) {
                token += 8;
                texopt->blendv = parseOnOff(&token, /* default */ true);
            } else if ((0 == strncmp(token, "-clamp", 6)) && IS_SPACE((token[6]))) {
                token += 7;
                texopt->clamp = parseOnOff(&token, /* default */ true);
            } else if ((0 == strncmp(token, "-boost", 6)) && IS_SPACE((token[6]))) {
                token += 7;
                texopt->sharpness = parseFloat(&token, 1.0);
            } else if ((0 == strncmp(token, "-bm", 3)) && IS_SPACE((token[3]))) {
                token += 4;
                texopt->bump_multiplier = parseFloat(&token, 1.0);
            } else if ((0 == strncmp(token, "-o", 2)) && IS_SPACE((token[2]))) {
                token += 3;
                parseFloat3(&(texopt->origin_offset[0]), &(texopt->origin_offset[1]),
                            &(texopt->origin_offset[2]), &token);
            } else if ((0 == strncmp(token, "-s", 2)) && IS_SPACE((token[2]))) {
                token += 3;
                parseFloat3(&(texopt->scale[0]), &(texopt->scale[1]), &(texopt->scale[2]),
                            &token, 1.0, 1.0, 1.0);
            } else if ((0 == strncmp(token, "-t", 2)) && IS_SPACE((token[2]))) {
                token += 3;
                parseFloat3(&(texopt->turbulence[0]), &(texopt->turbulence[1]),
                            &(texopt->turbulence[2]), &token);
            } else if ((0 == strncmp(token, "-type", 5)) && IS_SPACE((token[5]))) {
                token += 5;
                texopt->type = parseTextureType((&token), TEXTURE_TYPE_NONE);
            } else if ((0 == strncmp(token, "-imfchan", 8)) && IS_SPACE((token[8]))) {
                token += 9;
                token += strspn(token, " \t");
                const char *end = token + strcspn(token, " \t\r");
                if ((end - token) == 1) {  // Assume one char for -imfchan
                    texopt->imfchan = (*token);
                }
                token = end;
            } else if ((0 == strncmp(token, "-mm", 3)) && IS_SPACE((token[3]))) {
                token += 4;
                parseFloat2(&(texopt->brightness), &(texopt->contrast), &token, 0.0, 1.0);
            } else {
                // Assume texture filename
                token += strspn(token, " \t");         // skip space
                size_t len = strcspn(token, " \t\r");  // untile next space
                texture_name = std::string(token, token + len);
                token += len;
                
                token += strspn(token, " \t");  // skip space
                
                found_texname = true;
            }
        }
        
        if (found_texname) {
            (*texname) = texture_name;
            return true;
        } else {
            return false;
        }
    }
    
    static void InitMaterial(material_t *material) {
        material->name = "";
        material->ambient_texname = "";
        material->diffuse_texname = "";
        material->specular_texname = "";
        material->specular_highlight_texname = "";
        material->bump_texname = "";
        material->displacement_texname = "";
        material->alpha_texname = "";
        for (int i = 0; i < 3; i++) {
            material->ambient[i] = 0.f;
            material->diffuse[i] = 0.f;
            material->specular[i] = 0.f;
            material->transmittance[i] = 0.f;
            material->emission[i] = 0.f;
        }
        material->illum = 0;
        material->dissolve = 1.f;
        material->shininess = 1.f;
        material->ior = 1.f;
        
        material->roughness = 0.f;
        material->metallic = 0.f;
        material->sheen = 0.f;
        material->clearcoat_thickness = 0.f;
        material->clearcoat_roughness = 0.f;
        material->anisotropy_rotation = 0.f;
        material->anisotropy = 0.f;
        material->roughness_texname = "";
        material->metallic_texname = "";
        material->sheen_texname = "";
        material->emissive_texname = "";
        material->normal_texname = "";
        
        material->has_diffuse_color = false;
        material->has_illum = false;
        material->unknown_parameter.clear();
    }
    
    static bool exportFaceGroupToShape(
                                       shape_t *shape, const std::vector<std::vector<vertex_index> > &faceGroup,
                                       const std::vector<tag_t> &tags, const int material_id,
                                       const std::string &name, bool triangulate) {
        if (faceGroup.empty()) {
            return false;
        }
        
        // Flatten vertices and indices
        for (size_t i = 0; i < faceGroup.size(); i++) {
            const std::vector<vertex_index> &face = faceGroup[i];
            
            vertex_index i0 = face[0];
            vertex_index i1(-1);
            vertex_index i2 = face[1];
            
            size_t npolys = face.size();
            
            if (triangulate) {
                // Polygon -> triangle fan conversion
                for (size_t k = 2; k < npolys; k++) {
                    i1 = i2;
                    i2 = face[k];
                    
                    index_t idx0, idx1, idx2;
                    idx0.vertex_index = i0.v_idx;
                    idx0.normal_index = i0.vn_idx;
                    idx0.texcoord_index = i0.vt_idx;
                    idx1.vertex_index = i1.v_idx;
                    idx1.normal_index = i1.vn_idx;
                    idx1.texcoord_index = i1.vt_idx;
                    idx2.vertex_index = i2.v_idx;
                    idx2.normal_index = i2.vn_idx;
                    idx2.texcoord_index = i2.vt_idx;
                    
                    shape->mesh.indices.push_back(idx0);
                    shape->mesh.indices.push_back(idx1);
                    shape->mesh.indices.push_back(idx2);
                    
                    shape->mesh.num_face_vertices.push_back(3);
                    shape->mesh.material_ids.push_back(material_id);
                }
            } else {
                for (size_t k = 0; k < npolys; k++) {
                    index_t idx;
                    idx.vertex_index = face[k].v_idx;
                    idx.normal_index = face[k].vn_idx;
                    idx.texcoord_index = face[k].vt_idx;
                    shape->mesh.indices.push_back(idx);
                }
                
                shape->mesh.num_face_vertices.push_back(
                                                        static_cast<unsigned char>(npolys));
                shape->mesh.material_ids.push_back(material_id);  // per face
            }
        }
        
        shape->name = name;
        shape->mesh.tags = tags;
        
        return true;
    }
    
    // Split a string with specified delimiter character.
    // http://stackoverflow.com/questions/236129/split-a-string-in-c
    static void SplitString(const std::string &s, char delim, std::vector<std::string> &elems)
    {
        std::stringstream ss;
        ss.str(s);
        std::string item;
        while (std::getline(ss, item, delim)) {
            elems.push_back(item);
        }
    }
    
    void LoadMtl(std::shared_ptr<std::map<std::string, int>> material_map,
                 std::shared_ptr<std::vector<material_t>> materials, std::shared_ptr<std::istream> inStream) {
        // Create a default material anyway.
        material_t material;
        InitMaterial(&material);
        
        std::string linebuf;
        while (inStream->peek() != -1) {
            safeGetline(*inStream, linebuf);
            
            // Trim trailing whitespace.
            if (linebuf.size() > 0) {
                linebuf = linebuf.substr(0, linebuf.find_last_not_of(" \t") + 1);
            }
            
            // Trim newline '\r\n' or '\n'
            if (linebuf.size() > 0) {
                if (linebuf[linebuf.size() - 1] == '\n')
                    linebuf.erase(linebuf.size() - 1);
            }
            if (linebuf.size() > 0) {
                if (linebuf[linebuf.size() - 1] == '\r')
                    linebuf.erase(linebuf.size() - 1);
            }
            
            // Skip if empty line.
            if (linebuf.empty()) {
                continue;
            }
            
            // Skip leading space.
            const char *token = linebuf.c_str();
            token += strspn(token, " \t");
            
            assert(token);
            if (token[0] == '\0') continue;  // empty line
            
            if (token[0] == '#') continue;  // comment line
            
            // new mtl
            if ((0 == strncmp(token, "newmtl", 6)) && IS_SPACE((token[6]))) {
                // flush previous material.
                if (!material.name.empty()) {
                    material_map->insert(std::pair<std::string, int>(
                                                                     material.name, static_cast<int>(materials->size())));
                    materials->push_back(material);
                }
                
                // initial temporary material
                InitMaterial(&material);
                
                // set new mtl name
                char namebuf[TINYOBJ_SSCANF_BUFFER_SIZE];
                token += 7;
#ifdef _MSC_VER
                sscanf_s(token, "%s", namebuf, (unsigned)_countof(namebuf));
#else
                sscanf(token, "%s", namebuf);
#endif
                material.name = namebuf;
                continue;
            }
            
            // ambient
            if (token[0] == 'K' && token[1] == 'a' && IS_SPACE((token[2]))) {
                token += 2;
                float r, g, b;
                parseFloat3(&r, &g, &b, &token);
                material.ambient[0] = r;
                material.ambient[1] = g;
                material.ambient[2] = b;
                continue;
            }
            
            // diffuse
            if (token[0] == 'K' && token[1] == 'd' && IS_SPACE((token[2]))) {
                token += 2;
                float r, g, b;
                parseFloat3(&r, &g, &b, &token);
                material.diffuse[0] = r;
                material.diffuse[1] = g;
                material.diffuse[2] = b;
                
                material.has_diffuse_color = true;
                continue;
            }
            
            // specular
            if (token[0] == 'K' && token[1] == 's' && IS_SPACE((token[2]))) {
                token += 2;
                float r, g, b;
                parseFloat3(&r, &g, &b, &token);
                material.specular[0] = r;
                material.specular[1] = g;
                material.specular[2] = b;
                continue;
            }
            
            // transmittance
            if ((token[0] == 'K' && token[1] == 't' && IS_SPACE((token[2]))) ||
                (token[0] == 'T' && token[1] == 'f' && IS_SPACE((token[2])))) {
                token += 2;
                float r, g, b;
                parseFloat3(&r, &g, &b, &token);
                material.transmittance[0] = r;
                material.transmittance[1] = g;
                material.transmittance[2] = b;
                continue;
            }
            
            // ior(index of refraction)
            if (token[0] == 'N' && token[1] == 'i' && IS_SPACE((token[2]))) {
                token += 2;
                material.ior = parseFloat(&token);
                continue;
            }
            
            // emission
            if (token[0] == 'K' && token[1] == 'e' && IS_SPACE(token[2])) {
                token += 2;
                float r, g, b;
                parseFloat3(&r, &g, &b, &token);
                material.emission[0] = r;
                material.emission[1] = g;
                material.emission[2] = b;
                continue;
            }
            
            // shininess
            if (token[0] == 'N' && token[1] == 's' && IS_SPACE(token[2])) {
                token += 2;
                material.shininess = parseFloat(&token);
                continue;
            }
            
            // illum model
            if (0 == strncmp(token, "illum", 5) && IS_SPACE(token[5])) {
                token += 6;
                material.illum = parseInt(&token);
                material.has_illum = true;
                continue;
            }
            
            // dissolve
            if ((token[0] == 'd' && IS_SPACE(token[1]))) {
                token += 1;
                material.dissolve = parseFloat(&token);
                continue;
            }
            if (token[0] == 'T' && token[1] == 'r' && IS_SPACE(token[2])) {
                token += 2;
                // Invert value of Tr(assume Tr is in range [0, 1])
                material.dissolve = 1.0f - parseFloat(&token);
                continue;
            }
            
            // PBR: roughness
            if (token[0] == 'P' && token[1] == 'r' && IS_SPACE(token[2])) {
                token += 2;
                material.roughness = parseFloat(&token);
                continue;
            }
            
            // PBR: metallic
            if (token[0] == 'P' && token[1] == 'm' && IS_SPACE(token[2])) {
                token += 2;
                material.metallic = parseFloat(&token);
                continue;
            }
            
            // PBR: sheen
            if (token[0] == 'P' && token[1] == 's' && IS_SPACE(token[2])) {
                token += 2;
                material.sheen = parseFloat(&token);
                continue;
            }
            
            // PBR: clearcoat thickness
            if (token[0] == 'P' && token[1] == 'c' && IS_SPACE(token[2])) {
                token += 2;
                material.clearcoat_thickness = parseFloat(&token);
                continue;
            }
            
            // PBR: clearcoat roughness
            if ((0 == strncmp(token, "Pcr", 3)) && IS_SPACE(token[3])) {
                token += 4;
                material.clearcoat_roughness = parseFloat(&token);
                continue;
            }
            
            // PBR: anisotropy
            if ((0 == strncmp(token, "aniso", 5)) && IS_SPACE(token[5])) {
                token += 6;
                material.anisotropy = parseFloat(&token);
                continue;
            }
            
            // PBR: anisotropy rotation
            if ((0 == strncmp(token, "anisor", 6)) && IS_SPACE(token[6])) {
                token += 7;
                material.anisotropy_rotation = parseFloat(&token);
                continue;
            }
            
            // ambient texture
            if ((0 == strncmp(token, "map_Ka", 6)) && IS_SPACE(token[6])) {
                token += 7;
                ParseTextureNameAndOption(&(material.ambient_texname),
                                          &(material.ambient_texopt), token,
                                          /* is_bump */ false);
                continue;
            }
            
            // diffuse texture
            if ((0 == strncmp(token, "map_Kd", 6)) && IS_SPACE(token[6])) {
                token += 7;
                ParseTextureNameAndOption(&(material.diffuse_texname),
                                          &(material.diffuse_texopt), token,
                                          /* is_bump */ false);
                continue;
            }
            
            // specular texture
            if ((0 == strncmp(token, "map_Ks", 6)) && IS_SPACE(token[6])) {
                token += 7;
                ParseTextureNameAndOption(&(material.specular_texname),
                                          &(material.specular_texopt), token,
                                          /* is_bump */ false);
                continue;
            }
            
            // specular highlight texture
            if ((0 == strncmp(token, "map_Ns", 6)) && IS_SPACE(token[6])) {
                token += 7;
                ParseTextureNameAndOption(&(material.specular_highlight_texname),
                                          &(material.specular_highlight_texopt), token,
                                          /* is_bump */ false);
                continue;
            }
            
            // bump texture
            if ((0 == strncmp(token, "map_bump", 8)) && IS_SPACE(token[8])) {
                token += 9;
                ParseTextureNameAndOption(&(material.bump_texname),
                                          &(material.bump_texopt), token,
                                          /* is_bump */ true);
                continue;
            }
            
            // bump texture
            if ((0 == strncmp(token, "bump", 4)) && IS_SPACE(token[4])) {
                token += 5;
                ParseTextureNameAndOption(&(material.bump_texname),
                                          &(material.bump_texopt), token,
                                          /* is_bump */ true);
                continue;
            }
            
            // alpha texture
            if ((0 == strncmp(token, "map_d", 5)) && IS_SPACE(token[5])) {
                token += 6;
                material.alpha_texname = token;
                ParseTextureNameAndOption(&(material.alpha_texname),
                                          &(material.alpha_texopt), token,
                                          /* is_bump */ false);
                continue;
            }
            
            // displacement texture
            if ((0 == strncmp(token, "disp", 4)) && IS_SPACE(token[4])) {
                token += 5;
                ParseTextureNameAndOption(&(material.displacement_texname),
                                          &(material.displacement_texopt), token,
                                          /* is_bump */ false);
                continue;
            }
            
            // PBR: roughness texture
            if ((0 == strncmp(token, "map_Pr", 6)) && IS_SPACE(token[6])) {
                token += 7;
                ParseTextureNameAndOption(&(material.roughness_texname),
                                          &(material.roughness_texopt), token,
                                          /* is_bump */ false);
                continue;
            }
            
            // PBR: metallic texture
            if ((0 == strncmp(token, "map_Pm", 6)) && IS_SPACE(token[6])) {
                token += 7;
                ParseTextureNameAndOption(&(material.metallic_texname),
                                          &(material.metallic_texopt), token,
                                          /* is_bump */ false);
                continue;
            }
            
            // PBR: sheen texture
            if ((0 == strncmp(token, "map_Ps", 6)) && IS_SPACE(token[6])) {
                token += 7;
                ParseTextureNameAndOption(&(material.sheen_texname),
                                          &(material.sheen_texopt), token,
                                          /* is_bump */ false);
                continue;
            }
            
            // PBR: emissive texture
            if ((0 == strncmp(token, "map_Ke", 6)) && IS_SPACE(token[6])) {
                token += 7;
                ParseTextureNameAndOption(&(material.emissive_texname),
                                          &(material.emissive_texopt), token,
                                          /* is_bump */ false);
                continue;
            }
            
            // PBR: normal map texture
            if ((0 == strncmp(token, "norm", 4)) && IS_SPACE(token[4])) {
                token += 5;
                ParseTextureNameAndOption(
                                          &(material.normal_texname), &(material.normal_texopt), token,
                                          /* is_bump */ false);  // @fixme { is_bump will be true? }
                continue;
            }
            
            // unknown parameter
            const char *_space = strchr(token, ' ');
            if (!_space) {
                _space = strchr(token, '\t');
            }
            if (_space) {
                std::ptrdiff_t len = _space - token;
                std::string key(token, static_cast<size_t>(len));
                std::string value = _space + 1;
                material.unknown_parameter.insert(
                                                  std::pair<std::string, std::string>(key, value));
            }
        }
        // flush last material.
        material_map->insert(std::pair<std::string, int>(
                                                         material.name, static_cast<int>(materials->size())));
        materials->push_back(material);
    }
    
    bool MaterialFileReader::operator()(const std::string &matId,
                                        std::shared_ptr<std::vector<material_t>> materials,
                                        std::shared_ptr<std::map<std::string, int>> matMap,
                                        std::string *err) {
        std::string filepath;
        
        if (!m_mtlBaseDir.empty()) {
            filepath = std::string(m_mtlBaseDir) + "/" + matId;
        } else {
            filepath = matId;
        }
        
        // If we have a resource map, attempt to find the location where the mtl was downloaded to
        if (m_resourceMap != nullptr) {
            filepath = VROPlatformFindValueInResourceMap(matId, *m_resourceMap);
            return readMaterialFile(filepath, matId, materials, matMap, err);
        }
        
        // If the path is a URL, we have to download it to a temporary file
        else if (m_baseurl) {
            std::weak_ptr<VROTaskQueue> taskQueue_w = m_taskQueue;
            
            VROPlatformDispatchAsyncRenderer([taskQueue_w, filepath, matId, materials, matMap, err] {
                std::shared_ptr<VROTaskQueue> taskQueue = taskQueue_w.lock();
                if (!taskQueue) {
                    return;
                }
                
                taskQueue->addTask([taskQueue_w, filepath, matId, materials, matMap, err] {
                    VROPlatformDownloadURLToFileAsync(filepath,
                                                      [taskQueue_w, matId, materials, matMap, err](std::string path, bool isTemp) {
                                                          std::shared_ptr<VROTaskQueue> taskQueue_s = taskQueue_w.lock();
                                                          if (taskQueue_s) {
                                                              readMaterialFile(path, matId, materials, matMap, err);
                                                              taskQueue_s->onTaskComplete();
                                                          }
                                                          if (isTemp) {
                                                              VROPlatformDeleteFile(path);
                                                          }
                                                      },
                                                      [taskQueue_w, matId]() {
                                                          pinfo("Material map [%s] not downloaded", matId.c_str());
                                                          std::shared_ptr<VROTaskQueue> taskQueue_s = taskQueue_w.lock();
                                                          if (taskQueue_s) {
                                                              taskQueue_s->onTaskComplete();
                                                          }
                                                      });
                });
            });
        }
        return true;
    }
    
    bool MaterialFileReader::readMaterialFile(std::string filepath, const std::string &matId,
                                              std::shared_ptr<std::vector<material_t>> materials,
                                              std::shared_ptr<std::map<std::string, int>> matMap, std::string *err) {
        std::shared_ptr<std::ifstream> matIStream = std::make_shared<std::ifstream>(filepath.c_str());
        if (!matIStream) {
            std::stringstream ss;
            ss << "WARN: path to material [" << matId + "] not found" << std::endl;
            if (err) {
                (*err) += ss.str();
            }
            return false;
        }
        
        LoadMtl(matMap, materials, matIStream);
        return true;
    }
    
    void LoadObj(std::shared_ptr<attrib_t> attrib, std::shared_ptr<std::vector<shape_t>> shapes,
                 std::shared_ptr<std::vector<material_t>> materials, std::string *err,
                 const char *filename, const char *mtl_basedir, bool baseurl,
                 std::map<std::string, std::string> *resourceMap,
                 std::shared_ptr<VROTaskQueue> taskQueue,
                 std::function<void(bool)> onFinished,
                 bool triangulate) {
        attrib->vertices.clear();
        attrib->normals.clear();
        attrib->texcoords.clear();
        shapes->clear();
        
        std::shared_ptr<std::ifstream> ifs = std::make_shared<std::ifstream>(filename);
        if (!(*ifs)) {
            pinfo("Failed to open file %s for OBJ", filename);
            VROPlatformDispatchAsyncRenderer([onFinished] {
                onFinished(false);
            });
            return;
        }
        
        std::string baseDir;
        if (mtl_basedir) {
            baseDir = mtl_basedir;
        }
        
        // The material file reader includes a task queue. We will wait on this
        // task queue after reading the MTL files, so we know the MTL files are
        // fully loaded before running loadOBJ
        MaterialFileReader matFileReader;
        if (resourceMap != nullptr) {
            matFileReader = MaterialFileReader(resourceMap, taskQueue);
        } else {
            matFileReader = MaterialFileReader(baseDir, baseurl, taskQueue);
        }
        
        // Read the MTL libs in the file
        std::shared_ptr<std::map<std::string, int>> material_map = std::make_shared<std::map<std::string, int>>();
        LoadMTLFiles(materials, material_map, err, ifs, &matFileReader);
        pinfo("   MTL files queued for reading");
        // Reset the stream
        ifs->clear( );
        ifs->seekg( 0, std::ios::beg );

        std::weak_ptr<VROTaskQueue> taskQueue_w = taskQueue;

        // Read the rest of the OBJ after the MTL is finished. We have to switch
        // over to the rendering thread in order to wait on the task queue
        VROPlatformDispatchAsyncRenderer([attrib, shapes, material_map, err, ifs, triangulate, onFinished, taskQueue_w] {
            std::shared_ptr<VROTaskQueue> taskQueue_s = taskQueue_w.lock();
            if (taskQueue_s) {
                pinfo("   Reading MTL files (if any)...");
                taskQueue_s->processTasksAsync([attrib, shapes, material_map, err, ifs, triangulate, onFinished] {
                    pinfo("   MTL files read, loading OBJ");
                    bool ret = LoadObj(attrib, shapes, material_map, err, ifs, triangulate);
                    onFinished(ret);
                });
            }
        });
    }
    
    bool LoadObj(std::shared_ptr<attrib_t> attrib, std::shared_ptr<std::vector<shape_t>> shapes,
                 std::shared_ptr<std::map<std::string, int>> material_map,
                 std::string *err,
                 std::shared_ptr<std::istream> inStream,
                 bool triangulate) {
        
        std::vector<float> v;
        std::vector<float> vn;
        std::vector<float> vt;
        std::vector<tag_t> tags;
        std::vector<std::vector<vertex_index> > faceGroup;
        std::string name;
        
        // material
        int material = -1;
        
        shape_t shape;
        
        std::string linebuf;
        while (inStream->peek() != -1) {
            safeGetline(*inStream, linebuf);
            
            // Trim newline '\r\n' or '\n'
            if (linebuf.size() > 0) {
                if (linebuf[linebuf.size() - 1] == '\n')
                    linebuf.erase(linebuf.size() - 1);
            }
            if (linebuf.size() > 0) {
                if (linebuf[linebuf.size() - 1] == '\r')
                    linebuf.erase(linebuf.size() - 1);
            }
            
            // Skip if empty line.
            if (linebuf.empty()) {
                continue;
            }
            
            // Skip leading space.
            const char *token = linebuf.c_str();
            token += strspn(token, " \t");
            
            assert(token);
            if (token[0] == '\0') continue;  // empty line
            
            if (token[0] == '#') continue;  // comment line
            
            // vertex
            if (token[0] == 'v' && IS_SPACE((token[1]))) {
                token += 2;
                float x, y, z;
                parseFloat3(&x, &y, &z, &token);
                v.push_back(x);
                v.push_back(y);
                v.push_back(z);
                continue;
            }
            
            // normal
            if (token[0] == 'v' && token[1] == 'n' && IS_SPACE((token[2]))) {
                token += 3;
                float x, y, z;
                parseFloat3(&x, &y, &z, &token);
                vn.push_back(x);
                vn.push_back(y);
                vn.push_back(z);
                continue;
            }
            
            // texcoord
            if (token[0] == 'v' && token[1] == 't' && IS_SPACE((token[2]))) {
                token += 3;
                float x, y;
                parseFloat2(&x, &y, &token);
                vt.push_back(x);
                vt.push_back(y);
                continue;
            }
            
            // face
            if (token[0] == 'f' && IS_SPACE((token[1]))) {
                token += 2;
                token += strspn(token, " \t");
                
                std::vector<vertex_index> face;
                face.reserve(3);
                
                while (!IS_NEW_LINE(token[0])) {
                    vertex_index vi = parseTriple(&token, static_cast<int>(v.size() / 3),
                                                  static_cast<int>(vn.size() / 3),
                                                  static_cast<int>(vt.size() / 2));
                    face.push_back(vi);
                    size_t n = strspn(token, " \t\r");
                    token += n;
                }
                
                // replace with emplace_back + std::move on C++11
                faceGroup.push_back(std::vector<vertex_index>());
                faceGroup[faceGroup.size() - 1].swap(face);
                
                continue;
            }
            
            // use mtl
            if ((0 == strncmp(token, "usemtl", 6)) && IS_SPACE((token[6]))) {
                char namebuf[TINYOBJ_SSCANF_BUFFER_SIZE];
                token += 7;
#ifdef _MSC_VER
                sscanf_s(token, "%s", namebuf, (unsigned)_countof(namebuf));
#else
                sscanf(token, "%s", namebuf);
#endif
                
                int newMaterialId = -1;
                if (material_map->find(namebuf) != material_map->end()) {
                    newMaterialId = material_map->find(namebuf)->second;
                } else {
                    // { error!! material not found }
                }
                
                if (newMaterialId != material) {
                    // Create per-face material. Thus we don't add `shape` to `shapes` at
                    // this time.
                    // just clear `faceGroup` after `exportFaceGroupToShape()` call.
                    exportFaceGroupToShape(&shape, faceGroup, tags, material, name,
                                           triangulate);
                    faceGroup.clear();
                    material = newMaterialId;
                }
                
                continue;
            }
            
            // load mtl
            if ((0 == strncmp(token, "mtllib", 6)) && IS_SPACE((token[6]))) {
                // MTL files are read before processing the OBJ (in LoadMTLFiles)
                continue;
            }
            
            // group name
            if (token[0] == 'g' && IS_SPACE((token[1]))) {
                // flush previous face group.
                bool ret = exportFaceGroupToShape(&shape, faceGroup, tags, material, name,
                                                  triangulate);
                if (ret) {
                    shapes->push_back(shape);
                }
                
                shape = shape_t();
                
                // material = -1;
                faceGroup.clear();
                
                std::vector<std::string> names;
                names.reserve(2);
                
                while (!IS_NEW_LINE(token[0])) {
                    std::string str = parseString(&token);
                    names.push_back(str);
                    token += strspn(token, " \t\r");  // skip tag
                }
                
                assert(names.size() > 0);
                
                // names[0] must be 'g', so skip the 0th element.
                if (names.size() > 1) {
                    name = names[1];
                } else {
                    name = "";
                }
                
                continue;
            }
            
            // object name
            if (token[0] == 'o' && IS_SPACE((token[1]))) {
                // flush previous face group.
                bool ret = exportFaceGroupToShape(&shape, faceGroup, tags, material, name,
                                                  triangulate);
                if (ret) {
                    shapes->push_back(shape);
                }
                
                // material = -1;
                faceGroup.clear();
                shape = shape_t();
                
                // @todo { multiple object name? }
                char namebuf[TINYOBJ_SSCANF_BUFFER_SIZE];
                token += 2;
#ifdef _MSC_VER
                sscanf_s(token, "%s", namebuf, (unsigned)_countof(namebuf));
#else
                sscanf(token, "%s", namebuf);
#endif
                name = std::string(namebuf);
                
                continue;
            }
            
            if (token[0] == 't' && IS_SPACE(token[1])) {
                tag_t tag;
                
                char namebuf[4096];
                token += 2;
#ifdef _MSC_VER
                sscanf_s(token, "%s", namebuf, (unsigned)_countof(namebuf));
#else
                sscanf(token, "%s", namebuf);
#endif
                tag.name = std::string(namebuf);
                token += tag.name.size() + 1;
                
                tag_sizes ts = parseTagTriple(&token);
                
                tag.intValues.resize(static_cast<size_t>(ts.num_ints));
                for (size_t i = 0; i < static_cast<size_t>(ts.num_ints); ++i) {
                    tag.intValues[i] = atoi(token);
                    token += strcspn(token, "/ \t\r") + 1;
                }
                
                tag.floatValues.resize(static_cast<size_t>(ts.num_floats));
                for (size_t i = 0; i < static_cast<size_t>(ts.num_floats); ++i) {
                    tag.floatValues[i] = parseFloat(&token);
                    token += strcspn(token, "/ \t\r") + 1;
                }
                
                tag.stringValues.resize(static_cast<size_t>(ts.num_strings));
                for (size_t i = 0; i < static_cast<size_t>(ts.num_strings); ++i) {
                    char stringValueBuffer[4096];
                    
#ifdef _MSC_VER
                    sscanf_s(token, "%s", stringValueBuffer,
                             (unsigned)_countof(stringValueBuffer));
#else
                    sscanf(token, "%s", stringValueBuffer);
#endif
                    tag.stringValues[i] = stringValueBuffer;
                    token += tag.stringValues[i].size() + 1;
                }
                
                tags.push_back(tag);
            }
            
            // Ignore unknown command.
        }
        
        bool ret = exportFaceGroupToShape(&shape, faceGroup, tags, material, name,
                                          triangulate);
        // exportFaceGroupToShape return false when `usemtl` is called in the last
        // line.
        // we also add `shape` to `shapes` when `shape.mesh` has already some
        // faces(indices)
        if (ret || shape.mesh.indices.size()) {
            shapes->push_back(shape);
        }
        faceGroup.clear();  // for safety
        
        attrib->vertices.swap(v);
        attrib->normals.swap(vn);
        attrib->texcoords.swap(vt);
        
        return true;
    }
    
    bool LoadMTLFiles(std::shared_ptr<std::vector<material_t>> materials,
                      std::shared_ptr<std::map<std::string, int>> material_map,
                      std::string *err,
                      std::shared_ptr<std::istream> inStream, MaterialReader *readMatFn) {
        
        std::vector<float> v;
        std::vector<float> vn;
        std::vector<float> vt;
        std::vector<tag_t> tags;
        std::vector<std::vector<vertex_index> > faceGroup;
        std::string name;
        
        std::string linebuf;
        while (inStream->peek() != -1) {
            safeGetline(*inStream, linebuf);
            
            // Trim newline '\r\n' or '\n'
            if (linebuf.size() > 0) {
                if (linebuf[linebuf.size() - 1] == '\n')
                    linebuf.erase(linebuf.size() - 1);
            }
            if (linebuf.size() > 0) {
                if (linebuf[linebuf.size() - 1] == '\r')
                    linebuf.erase(linebuf.size() - 1);
            }
            
            // Skip if empty line.
            if (linebuf.empty()) {
                continue;
            }
            
            // Skip leading space.
            const char *token = linebuf.c_str();
            token += strspn(token, " \t");
            
            assert(token);
            if (token[0] == '\0') continue;  // empty line
            
            if (token[0] == '#') continue;  // comment line
            
            // load mtl
            if ((0 == strncmp(token, "mtllib", 6)) && IS_SPACE((token[6]))) {
                if (readMatFn) {
                    token += 7;
                    
                    std::vector<std::string> filenames;
                    SplitString(std::string(token), ' ', filenames);
                    
                    if (filenames.empty()) {
                        if (err) {
                            (*err) += "WARN: Looks like empty filename for mtllib. Use default material. \n";
                        }
                    } else {
                        bool found = false;
                        for (size_t s = 0; s < filenames.size(); s++) {
                            
                            std::string err_mtl;
                            bool ok = (*readMatFn)(filenames[s].c_str(), materials, material_map,
                                                   &err_mtl);
                            pinfo("   Queued reading of material file [%s]", filenames[s].c_str());
                            if (err && (!err_mtl.empty())) {
                                (*err) += err_mtl; // This should be warn message.
                            }
                            
                            if (ok) {
                                found = true;
                                break;
                            }
                        }
                        
                        if (!found) {
                            if (err) {
                                (*err) += "WARN: Failed to load material file(s). Use default material.\n";
                            }
                        }
                    }
                }
                continue;
            }
            // Ignore unknown command.
        }
        
        return true;
    }
}  // namespace tinyobj

#endif

#endif  // TINY_OBJ_LOADER_H_
